Chicken Flocks Harbor Superbug

Add chickens to the list of farm animals that are harboring MRSA, or methicillin-resistant Staphylococcus aureus, a formerly rare bacteria found mostly in hospitals but now spreading far and wide.

More than 90,000 people become ill and 18,000 die each year from MRSA infections in the U.S., by one recent estimate. There's growing evidence that industrial-scale livestock operations may help sustain the bacteria and expose people to infection.

MRSA bacteria showed up in broiler chickens at two out of 14 farms tested in Belgium, according to an upcoming report in Emerging Infectious Diseases.

The bacterial strain matched one previously found widely in pigs in the U.S., Canada, Denmark and the Netherlands. Tests in the chicken study showed the staph bacteria could defend itself from seven kinds of antiobiotic.

While there's no official reports of MRSA in U.S. chicken flocks, the bacteria has gained a foothold at hog-raising farms in this country. Researchers in Iowa found MRSA in 49 percent of 299 pigs tested at two large-scale pork producers. The bacteria also showed up in nine of 14 workers tested at one of the sites, researchers reported last month in the journal PLoS One.

None of the workers became ill, but the strain has caused human infections in The Netherlands -- justifying concerns that livestock could serve as a reservoir for spreading illness among people.

Livestock growers routinely feed a variety of antibiotics to hogs, cattle and poultry to boost growth. Studies have found that the practice can promote the rise of drug-resistant bacterial strains. The European Union banned the use of antibiotics as growth promoters three years ago, and the U.S. was set to follow suit, but the Food and Drug Administration made a last-minute reversal in December which allows the continued use of cephalosporin antibiotics in food-producing animals.